A study of bone loss in 17 astronauts flying aboard the International Space Station provides a fuller understanding of the effects of space travel on the human body and steps it can mitigate, crucial knowledge for potentially ambitious future missions.
The study collects new data on bone loss in astronauts caused by the microgravity conditions of space and the extent to which bone mineral density can be recovered on Earth. It contained 14 male and three female astronauts, average age 47, whose missions ranged from four to seven months in space, with an average of about 5-1 / 2 months.
One year after returning to Earth, astronauts showed, on average, 2.1% reduced bone mineral density near the tibia – one of the lower leg bones – and 1.3% reduced bone strength. Nine have not regained the bone mineral density after space flight, with permanent loss.
“We know that astronauts lose bones during long-term spaceflight. What’s new about this study is that we track astronauts one year after their space journey to understand if and how bones recover,” said Professor Leigh Gabel of the University of Calgary, an exercise scientist who was the lead author of the study published this week in the journal Scientific Reports.
“Astronauts experienced significant bone loss during six months of space flight – a loss we would expect to see in older adults more than two decades on Earth, and they have only recovered about half of that loss after one year back on Earth,” Gabel said.
Bone loss occurs because bones that are typically earth-bearing would not carry weight in space. Space agencies will need to improve countermeasures – exercise regimen and nutrition – to prevent bone loss, Gabel said.
“During space flight, fine bone structures become thin, and eventually some of the bone rods become detached from each other. Once the astronaut returns to Earth, the remaining bone joints can thicken and strengthen, but those that are detached in space can not be rebuilt, so the overall bone structure of the astronaut changes permanently, “said Gabel.
The study’s astronauts have been flying in space for the past seven years. The study did not reveal their nationalities, but they were from the US space agency NASA, Canadian Space Agency, European Space Agency and Japan Aerospace Exploration Agency.
Space travel poses several challenges for the human body – important concerns for space agencies as they plan new explorations. For example, NASA intends to send astronauts back to the moon, a mission now planned for 2025 at its earliest. That could be a prelude to future astronaut missions to Mars or a longer-term presence on the lunar surface.
“Microgravity affects many body systems, muscles and bones are among them,” Gabel said.
“The cardiovascular system also experiences many changes. Without the force of gravity that draws blood to our feet, astronauts experience a fluid shift that causes more blood to pool in the upper body. This can affect the cardiovascular system and vision.
“Radiation is also a major health concern for astronauts, because the farther they travel from Earth, the greater exposure to solar radiation and increased cancer risk,” Gabel said.
The study showed that longer space missions resulted in both more bone loss and a lower chance of bone recovery thereafter. Exercise in flight – resistance training on the space station – proved to be important in preventing muscle and bone loss. Astronauts who performed more deadlifts compared to what they would normally do on Earth were found to be more likely to recover bones after the mission.
“There’s a lot we still do not know about how microgravity affects human health, especially on space missions longer than six months, and about the long-term health consequences,” Gabel said. “We really hope that bone loss will eventually plateau on longer missions, that people will stop losing bones, but we do not know.”
Astronaut study reveals effects of space travel on human bones – SABC News
Source link Astronaut study reveals effects of space travel on human bones – SABC News